Effect of Endotoxemia in Suckling Rats on Pancreatic Integrity and Exocrine Function in Adults: A Review Report

Abstract

Background. Endotoxin (LPS), the component of Gram-negative bacteria, is responsible for sepsis and neonatal mortality, but low concentrations of LPS produced tissue protection in experimental studies. The effects of LPS applied to the suckling rats on the pancreas of adult animals have not been previously explored. We present the impact of neonatal endotoxemia on the pancreatic exocrine function and on the acute pancreatitis which has been investigated in the adult animals. Endotoxemia was induced in suckling rats by intraperitoneal application of LPS from Escherichia coli or Salmonella typhi. In the adult rats, pretreated in the early period of life with LPS, histological manifestations of acute pancreatitis have been reduced. Pancreatic weight and plasma lipase activity were decreased, and SOD concentration was reversed and accompanied by a significant reduction of lipid peroxidation products (MDA + 4 HNE) in the pancreatic tissue. In the pancreatic acini, the significant increases in protein signals for toll-like receptor 4 and for heat shock protein 60 were found. Signal for the CCK1 receptor was reduced and pancreatic secretory responses to caerulein were diminished, whereas basal enzyme secretion was unaffected. These pioneer studies have shown that exposition of suckling rats to endotoxin has an impact on the pancreas in the adult organism.

Figure 1

Results of an in vivo study—amylase responses to caerulein (1 μg/kg i.p.) in adult rats, which have been subjected in the suckling period of life to endotoxin from E. coli or S. typhi given at total doses of 25, 50, or 75 mg/kg. C—normal control. Results are means ± SEM from 4 separate experiments, each performed on 6 rats. The asterisk indicates a significant (p < 0.05) decrease below the value obtained from rats untreated with LPS and stimulated with caerulein.

Figure 2

Study in vitro—amylase release from isolated pancreatic acini with or without caerulein stimulation. Acini were isolated from the adult rats, which have been subjected in the suckling period of life to endotoxin from E. coli or S. typhi given at a total dose of 75 mg/kg. C—control. Results are means ± SEM from 4 separate experiments, each performed in duplicate. The asterisk indicates a significant (p < 0.05) decrease below the value obtained from control rats untreated with LPS.

Figure 3

Western blot analysis of CCK1 receptor protein level in the isolated pancreatic acini obtained from the adult rats which have been subjected in the suckling period of life to endotoxin from E. coli given at total doses of 25, 50, or 75 mg/kg. Control—intact rats. Results are means ± SEM from 6 separate experiments. The cross indicates a significant (p < 0.05) decrease below the control value. The asterisk indicates a significant (p < 0.05) decrease below the control. The blots were stripped and probed with GAPDH to document equal protein loading. The results were obtained in 4 consecutive experiments and are representative for the observed phenomenon.

Figure 4

Histological picture of pancreatic tissue taken from control rats (a), from rats subjected to acute caerulein-induced pancreatitis (b), and from the animals with or without acute pancreatitis subjected in the suckling period of life to endotoxin from E. coli (c) or S. typhi (d) given at a total dose of 75 mg/kg. Hematoxylin and eosin stain.

Figure 5

Interleukin 1β plasma concentration in adult rats with acute caerulein-induced pancreatitis alone and in animals, which have been subjected in the suckling period of life to endotoxin from E. coli or S. typhi given at total doses of 25, 50, or 75 mg/kg. Control—intact animals. Results are means ± SEM from 6–8 separate experiments, each performed on 6 rats. The asterisk indicates a significant (p < 0.05) decrease below the value obtained from rats with acute pancreatitis untreated with LPS.

Figure 6

Interleukin 10 plasma concentration in adult rats with acute caerulein-induced pancreatitis alone and in animals, which have been subjected in the suckling period of life to endotoxin from E. coli or S. typhi given at total doses of 25, 50, or 75 mg/kg. Control—intact animals. Results are means ± SEM from 6 separate experiments, each performed on 6 rats. The asterisk indicates a significant (p < 0.05) increase above the value obtained from rats with acute pancreatitis untreated with LPS.

Figure 7

Concentration of SOD in the pancreatic tissue taken from adult rats with acute caerulein-induced pancreatitis alone and from animals, which have been subjected in the suckling period of life to endotoxin from E. coli or S. typhi given at total doses of 25, 50, or 75 mg/kg. Control—intact rats. Results are means ± SEM from 6 separate experiments, each performed on 6–8 rats. The asterisk indicates a significant (p < 0.05) increase above the value obtained from rats with acute pancreatitis untreated with LPS.

Figure 8

Western blot analysis of HSP60 protein level in the isolated pancreatic acini obtained from the adult rats which have been subjected in the suckling period of life to endotoxin from E. coli given at total doses of 25, 50, or 75 mg/kg. Control—intact rats. Results are means ± SEM from 6 separate experiments. The asterisk indicates a significant (p < 0.05) increase above the control value. The cross indicates a significant (p < 0.05) decrease below the control. The blots were stripped and probed with GAPDH to document equal protein loading. The results were obtained in 4 consecutive experiments and are representative for the observed phenomenon.

Figure 9

Western blot analysis of TLR4 protein level in the isolated pancreatic acini obtained from the adult rats which have been subjected in the suckling period of life to endotoxin from E. coli given at total doses of 25, 50, or 75 mg/kg. Control—intact rats. Results are means ± SEM from 6 separate experiments. The asterisk indicates a significant (p < 0.05) increase above the control value. The cross indicates a significant (p < 0.05) decrease below the control. The blots were stripped and probed with GAPDH to document equal protein loading. The results were obtained in 4 consecutive experiments and are representative for the observed phenomenon.